Twenty meters of burnt wall beneath a courtyard of the Hôtel-Dieu. For the first time, Gallic Lutetia ceases to be a textual hypothesis.

Since February, a team led by David Couturier, from the Department of Architectural History and Archaeology in Paris, has been excavating the subsoil of the Hôtel-Dieu courtyards with the French National Institute for Preventive Archaeological Research (INRAP), under the supervision of the Regional Directorate of Cultural Affairs (DRAC) of Île-de-France, prior to the restructuring of the hospital site. Ancient dwellings, roads, and medieval layers were expected. Instead, a stone and timber wall, typical of Gallic fortifications, was found.

Twenty meters long. A charred facing, burnt seeds, the remains of a wooden building destroyed by fire just in front of it, and behind it, an artificial platform two meters thick, filled with sand and gravel. At the foot of the wall, a Gallic spearhead. Initial carbon-14 dating of the wood suggests a date range between 200 and 10 BC.

Until now, Gallic Lutetia existed only in Caesar's writings. In 53 BC, he convened an assembly of Gauls there. The following year, his lieutenant Labienus confronted the Parisii, who burned their own oppidum rather than surrender it to the legions. No material evidence had ever confirmed that this oppidum was located on the Île de la Cité, to the point that some had searched for it in Nanterre. The traces of fire found on the wall fit the narrative.

"This discovery fills an archaeological gap," summarizes Stéphane Deschamps, regional curator of archaeology at the DRAC Île-de-France. Caution is still advised: the function and chronology of the wall must still be verified. But the convergence of clues—the interlocking beam architecture, the contemporary ceramics of César, the fire—is difficult to ignore.

The question of what will happen next remains. Too fragile, too deep, the remains cannot stay in place during the construction. A mold will be made, and a section of the wall will be reconstructed with original stones to be shown to the public, accompanied by a three-dimensional reconstruction. Neither the date nor the location has yet been announced.

Paris knew it was born on an island. It is learning that it was born behind a wall.